1. Field of the Invention
The present invention relates to a method and an apparatus for stereoscopic image display and, in particular, relates to a method and an apparatus for stereoscopic image display with which an observer can observe a stereoscopic image without wearing special spectacles and which are preferred for displaying a stereoscopic image in a television, a video camera, a computer, a game machine or the like.
2. Related Background Art
Conventionally, the parallax barrier method and the lenticular method are known as methods of performing stereoscopic image display on an image displaying device such as a CRT or an LCD. With these methods, a stereoscopic image is displayed by displaying a synthesized stripe parallax image in which parallax images of two or more viewpoints, which are divided in a stripe pattern, are arranged alternately in a predetermined order, and guiding display light from the parallax image only to a viewpoint position corresponding to the parallax image in an optical member disposed in the front of the image displaying device. In addition, a method and an apparatus for stereoscopic image display is proposed in, for example, Japanese Patent Application Laid-Open No. 9-311294 which is characterized by transmitting light from an illumination light source through an optical modulator having a predetermined light transmitting section and a light shielding section and patterning the transmitted luminous flux, giving the patterned luminous flux directivity by a patterned optical system such that it becomes incident on the right and the left eyes of an observer separately, providing an image displaying device of a transmitting type between the patterned optical system and the observer, and synthesizing parallax images corresponding to the right and the left eyes alternately in a stripe pattern on the image displaying device to display.
In the parallax barrier method and the lenticular method, a vertical stripe synthesized parallax image in which long and narrow parallax images are alternately displayed in the vertical direction is used as a synthesized stripe parallax image. Orientation to a viewpoint of the parallax image is performed by a pixel position of the vertical stripe image and a parallax barrier or a lenticular lens placed in the front of an image displaying device. When an image displaying device having discrete pixels such as a CRT, an LCD or a PDP is used as an image displaying device in these methods, a dark part to which display light does not reach is generated on an observation surface corresponding to a part of a so-called black matrix existing between the pixels, and a width in the horizontal direction of an effective observation region is narrowed.
In the method proposed in Japanese Patent Application Laid-Open No. 9-311294, a transmitting type image displaying device such as an LCD is used as an image displaying device, and orientation of display light to a position of the left and the right eyes is performed by an optical system placed behind the image displaying device. This method has a problem such as cross talk that occurs when a direction of display light is disarranged by diffusion of a transmitting type image displaying device such as an LCD or diffraction due to a pixel structure.
In addition, in these conventional stereoscopic image displaying methods without spectacles, there is another problem in that the number of display pixels are halved when parallax images for each of the left and the right eyes are displayed, and resolution is decreased.